Immanuel Velikovsky says,
"It is not unthinkable that sometime before the age the record of ancient civilizations reaches, Uranus, together with Neptune, Saturn and Jupiter, formed a quadruple system that was captured by the sun and from which the planets of the solar system had their origin..."
This is very interesting that Velikovsky had worked out, based on his successful brown dwarf planetary capture model, that there could be
systems of multiple substellar objects. (I am assuming that he thought they were substellar, not main sequence stars, before capture. That seems obvious, but I could be wrong.)
It did turn out that red dwarf stars and brown dwarfs are found most often in binary systems:
Starting in 1995, astronomers have been able to detect a few nearby brown dwarfs. All of the brown dwarfs discovered so far are parts of a binary system. A binary system is one in which two stars orbit around one another (just like the planets of our solar system orbit our star, the Sun).
Visible light images of brown dwarf in binary system [with a red dwarf star companion]
as detected by Palomar Observatory and Hubble space Telescope
So why would we care about brown dwarfs? It is possible that a great deal of the mass in the universe is in the form of brown dwarfs, and since they do not give off much light, they could constitute part of the "missing mass" problem faced by cosmology.
Now the last statement sounds a bit like wishful thinking, which casts some doubt for me on the actual numbers of brown dwarfs in the Milky Way. But even if they are not as numerous as all that, it is not unthinkable that a binary brown dwarf system could cross the heliosphere surrounding our Sun.
“Oh for shame, how these mortals put the blame upon us gods, for they say evils come from us, when it is they rather who by their own recklessness win sorrow beyond what is given…”
~Homer